At the time I used very low cost GQRP 14.060MHz crystals, pulled up a little bit. For FT8 you would need low cost crystals at half 28.074MHz. The audio parts alone might give someone ideas.
15 Jan 2020
Polyakov RX idea
For modes like WSPR, FT8 and similar you may find inspiration in this very simple RX designed many years ago for 10m WSPR. Although direct conversion and hence DSB, it worked well.
At the time I used very low cost GQRP 14.060MHz crystals, pulled up a little bit. For FT8 you would need low cost crystals at half 28.074MHz. The audio parts alone might give someone ideas.
At the time I used very low cost GQRP 14.060MHz crystals, pulled up a little bit. For FT8 you would need low cost crystals at half 28.074MHz. The audio parts alone might give someone ideas.
Direct conversion can be single signal.
ReplyDeleteYou just add a crystal filter on the signal frequency. Completely useless if you need to tune the band, it's fine if you need one frequency.
Fifty years ago there was a guy from British Columbia building direct conversion SSB transceivers, for missionaries if I recall. He was actually opening up hc/6 crystals and adjusting them. And this was before ladder filters made their mark, so they were lattice filters where you needed crystals a few KHz apart to match the bandwidth.
Quite so Michael although it would probably significantly increase the cost!
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